REPL Predef intervention

[som-snytt]

It works globally but not with the obvious syntax.

scala> import Predef.{any2stringadd => _, _} ; new Object() + " argh"
import Predef.{any2stringadd=>_, _}
res1: String = java.lang.Object@32120956 argh

scala> import Predef.{any2stringadd => _, _}
import Predef.{any2stringadd=>_, _}

scala> new Object() + " argh"
<console>:14: error: value + is not a member of Object
       new Object() + " argh"
                    ^

[som-snytt]

Worth adding that this is still an issue after the demise of any2stringadd.

[som-snytt]

Code comment is

var predefEscapes = false      // only emit predef import header if name not resolved in history, loosely
predefEscapes = wanted contains PredefModule.name

so it's name-based.

$ scala
Welcome to Scala 2.13.1 (OpenJDK 64-Bit Server VM, Java 11.0.3).
Type in expressions for evaluation. Or try :help.

scala> import Predef.{assert=>_,_} ; assert(true)
import Predef.{assert=>_, _}

scala> :quit
amarki@amarki-462836:~/snips$ scala
Welcome to Scala 2.13.1 (OpenJDK 64-Bit Server VM, Java 11.0.3).
Type in expressions for evaluation. Or try :help.

scala> import Predef.{assert=>_,_}
import Predef.{assert=>_, _}

scala> assert(true)
       ^
       error: not found: value assert

scala> :quit
amarki@amarki-462836:~/snips$ scala
Welcome to Scala 2.13.1 (OpenJDK 64-Bit Server VM, Java 11.0.3).
Type in expressions for evaluation. Or try :help.

scala> import scala.Predef.{assert=>_,_}
import scala.Predef.{assert=>_, _}

scala> assert(true)

i.e.

scala> assert(true)
package $line4 {
  object $read extends _root_.scala.AnyRef {
    def <init>() = {
      super.<init>;
      ()
    };
    object $iw extends scala.AnyRef {
      def <init>() = {
        super.<init>;
        ()
      };
      object $iw extends scala.AnyRef {
        def <init>() = {
          super.<init>;
          ()
        };
        import scala.Predef.{assert=>_, _};
        object $iw extends scala.AnyRef {
          def <init>() = {
            super.<init>;
            ()
          };
          object $iw extends scala.AnyRef {
            def <init>() = {
              super.<init>;
              ()
            };
            val res0 = assert(true)
          }
        }
      }
    }
  }
}
Set symbol of res0 to val res0: Unit

[som-snytt]

OTOH,

$ scala
Welcome to Scala 2.13.1 (OpenJDK 64-Bit Server VM, Java 11.0.3).
Type in expressions for evaluation. Or try :help.

scala> object Predef { def haha = "hi" }
defined object Predef

scala> Predef.haha
res0: String = hi

scala> import Predef._
import Predef._

scala> haha
       ^
       error: not found: value haha

scala> $line3.$read.$iw.$iw.Predef.haha
res2: String = hi

scala> import $line3.$read.$iw.$iw.Predef.haha ; haha
import Predef.haha
res3: String = hi

scala> import $line3.$read.$iw.$iw.Predef._ ; haha
import Predef._
res4: String = hi

[som-snytt]

Oh, "haha", indeed.

scala> haha
package $line10 {
  object $read extends _root_.scala.AnyRef {
    def <init>() = {
      super.<init>;
      ()
    };
    object $iw extends scala.AnyRef {
      def <init>() = {
        super.<init>;
        ()
      };
      import $line3.$read.$iw.$iw.Predef;
      object $iw extends scala.AnyRef {
        def <init>() = {
          super.<init>;
          ()
        };
        val res2 = haha
      }
    }
  }
}
       ^
       error: not found: value haha

[som-snytt]

I see I was let off the hook, but the "rooted REPL" PR should address this issue.

[som-snytt]

That PR did not happen.

scala/scala#8593

The issue is an example of, "The REPL should work like normal code because that is its purpose, but it must be designed that way."